From patchwork Tue Feb 14 12:51:50 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Charan Teja Kalla X-Patchwork-Id: 56906 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:adf:eb09:0:0:0:0:0 with SMTP id s9csp2951766wrn; Tue, 14 Feb 2023 04:55:35 -0800 (PST) X-Google-Smtp-Source: AK7set9ZbeFxLsx87nvfZ7lIFRHZJznDmK3HHmxAexkPW4Jp/2TZjvFFVRiM090JGz9nPgeTl2fq X-Received: by 2002:a17:90b:1d09:b0:230:c272:3cfa with SMTP id on9-20020a17090b1d0900b00230c2723cfamr2427963pjb.22.1676379335160; Tue, 14 Feb 2023 04:55:35 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1676379335; cv=none; d=google.com; s=arc-20160816; b=gVRokkkOxG+z4obOY5edMNelYM/IJB68DBBJAzWpXaqeOcn8/DD3CcJ3AyCqa2EQrR ubTuo+Vo1Bks30LCQKQGf+5rcNtB0SB5y8h5ZO05sCGjk+58mlGE9kzbvUIi6D2jG7Po /Yqv//6GWCn/WPqGSCZttK2wRd8mURdifDfutMSpA97fuc/CbQRuTwq7jQawFb7qX8Yz Sl6IoLjMTGdD3B/gZ3O/tyV0+FO0J4ZIVI6QC+wr5NgHe6H+pqRBDkkDWuScmhLs7fBR xnWUS9/P07cpwFDnGDyrppuCCqwzwKZgkpQFCUcNG5mYsLav4RUjSqEbm/LsGrTWUwzd hX3g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:mime-version:references:in-reply-to:message-id :date:subject:cc:to:from:dkim-signature; bh=JDq/ueEkbIbP+lrfh4M3Gp48ayIRGMZZPUqNDXRi5Dc=; b=giHgor3pjF/7/Grt+3VPGNacA0z/GO+lIWEgMwCjpv7fCfly5VxlMZDeiftKNVsJQw Iry4F1ucttlFCXSjkz2JR1PmjMr5XyqjgsH+xj02NPbGk0S2zvbrmkaVyXd0qrgfgtWg rxh63ebHim5jTeF3+u3DQwl6ISUS/7wan05X82mDEk1ucuIjxv+r+2HAA3T6JEHXBUW/ /krNEFYrClnZczlVtICl2hiw/KOk8qyC6AT4VN7ikPVlSoAUiJwoMUqfPJ1+DoSKsPIP KzUCNNmYh24kVlNhbXhPPrEzoWz7U8bTKkzASUcCxnWDcTgfEZiTfpq5QpIXiRQ2yJqW pr1Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@quicinc.com header.s=qcppdkim1 header.b=WQmBCtI9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=quicinc.com Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id x9-20020a17090a2b0900b00233ce76f19dsi8532010pjc.11.2023.02.14.04.55.23; Tue, 14 Feb 2023 04:55:35 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@quicinc.com header.s=qcppdkim1 header.b=WQmBCtI9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=quicinc.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232123AbjBNMx2 (ORCPT + 99 others); Tue, 14 Feb 2023 07:53:28 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38336 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231944AbjBNMxW (ORCPT ); Tue, 14 Feb 2023 07:53:22 -0500 Received: from mx0a-0031df01.pphosted.com (mx0a-0031df01.pphosted.com [205.220.168.131]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F164B1715E for ; Tue, 14 Feb 2023 04:53:20 -0800 (PST) Received: from pps.filterd (m0279862.ppops.net [127.0.0.1]) by mx0a-0031df01.pphosted.com (8.17.1.19/8.17.1.19) with ESMTP id 31E1NvtU032334; Tue, 14 Feb 2023 12:53:02 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-type; s=qcppdkim1; bh=JDq/ueEkbIbP+lrfh4M3Gp48ayIRGMZZPUqNDXRi5Dc=; b=WQmBCtI9wa4AHzPfVczcQ7pKrMyreObZGLRLRMsPp8MecGXDKbDLyg6fEJUvOSNjOWc3 YEpCvafMI8Ie/PGMHLijjEyjVQhmyZYFiC7AWdXJoHdGksdxUxCd8UCmLNZ1PiUp6BAk 0F67ocBhkqQ0fa6klEetr9PLMbA+BhV6Dein+teN3Qvj+TGqgjXon1MI3Cs0IBN43ULg uHF5KJ/V50eqVQHu6z5OWMqCll4z00qc6KhXBXqB0jdt7WJYXWDVPxp/MrnPFrMTibTV h37qwYXJBBkzyeWYppUeBWRYxK2OG3jCk3ybGIgJ8+BXDInZUe087d/gTkmrUlyVMU4B 2Q== Received: from nalasppmta03.qualcomm.com (Global_NAT1.qualcomm.com [129.46.96.20]) by mx0a-0031df01.pphosted.com (PPS) with ESMTPS id 3nqyygsg97-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 14 Feb 2023 12:53:02 +0000 Received: from nalasex01a.na.qualcomm.com (nalasex01a.na.qualcomm.com [10.47.209.196]) by NALASPPMTA03.qualcomm.com (8.17.1.5/8.17.1.5) with ESMTPS id 31ECr0Cp028310 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 14 Feb 2023 12:53:01 GMT Received: from hu-charante-hyd.qualcomm.com (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.36; Tue, 14 Feb 2023 04:52:57 -0800 From: Charan Teja Kalla To: , , , , , , , CC: , , Charan Teja Kalla Subject: [PATCH V7 2/2] mm: shmem: implement POSIX_FADV_[WILL|DONT]NEED for shmem Date: Tue, 14 Feb 2023 18:21:50 +0530 Message-ID: <631e42b6dffdcc4b4b24f5be715c37f78bf903db.1676378702.git.quic_charante@quicinc.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: References: MIME-Version: 1.0 X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) X-QCInternal: smtphost X-Proofpoint-Virus-Version: vendor=nai engine=6200 definitions=5800 signatures=585085 X-Proofpoint-ORIG-GUID: leefWwIWmqXmGj62RbPU0f0AVox5AREK X-Proofpoint-GUID: leefWwIWmqXmGj62RbPU0f0AVox5AREK X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.219,Aquarius:18.0.930,Hydra:6.0.562,FMLib:17.11.170.22 definitions=2023-02-14_07,2023-02-14_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 suspectscore=0 phishscore=0 impostorscore=0 malwarescore=0 adultscore=0 mlxlogscore=999 mlxscore=0 priorityscore=1501 lowpriorityscore=0 spamscore=0 bulkscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2212070000 definitions=main-2302140111 X-Spam-Status: No, score=-2.8 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_LOW,SPF_HELO_NONE, SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1757811137455690873?= X-GMAIL-MSGID: =?utf-8?q?1757811137455690873?= Currently fadvise(2) is supported only for the files that doesn't associated with noop_backing_dev_info thus for the files, like shmem, fadvise results into NOP. But then there is file_operations->fadvise() that lets the file systems to implement their own fadvise implementation. Use this support to implement some of the POSIX_FADV_XXX functionality for shmem files. This patch aims to implement POSIX_FADV_WILLNEED and POSIX_FADV_DONTNEED advices to shmem files which can be helpful for the clients who may want to manage the shmem pages of the files that are created through shmem_file_setup[_with_mnt](). One usecase is implemented on the Snapdragon SoC's running Android where the graphics client is allocating lot of shmem pages per process and pinning them. When this process is put to background, the instantaneous reclaim is performed on those shmem pages using the logic implemented downstream[3][4]. With this patch, the client can now issue the fadvise calls on the shmem files that does the instantaneous reclaim which can aid the use cases like mentioned above. This usecase lead to ~2% reduction in average launch latencies of the apps and 10% in total number of kills by the low memory killer running on Android. Some questions asked while reviewing this patch: Q) Can the same thing be achieved with FD mapped to user and use madvise? A) All drivers are not mapping all the shmem fd's to user space and want to manage them with in the kernel. Ex: shmem memory can be mapped to the other subsystems and they fill in the data and then give it to other subsystem for further processing, where, the user mapping is not at all required. A simple example, memory that is given for gpu subsystem which can be filled directly and give to display subsystem. And the respective drivers know well about when to keep that memory in ram or swap based on may be a user activity. Q) Should we add the documentation section in Manual pages? A) The man[1] pages for the fadvise() whatever says is also applicable for shmem files. so couldn't feel it correct to add specific to shmem files separately. Q) The proposed semantics of POSIX_FADV_DONTNEED is actually similar to MADV_PAGEOUT and different from MADV_DONTNEED. This is a user facing API and this difference will cause confusion? A) man pages [2] says that "POSIX_FADV_DONTNEED attempts to free cached pages associated with the specified region." This means on issuing this FADV, it is expected to free the file cache pages. And it is implementation defined If the dirty pages may be attempted to writeback. And the unwritten dirty pages will not be freed. So, FADV_DONTNEED also covers the semantics of MADV_PAGEOUT for file pages and there is no purpose of PAGEOUT for file pages. [1] https://linux.die.net/man/2/fadvise [2] https://man7.org/linux/man-pages/man2/posix_fadvise.2.html [3] https://git.codelinaro.org/clo/la/platform/vendor/qcom/opensource/graphics-kernel/-/blob/gfx-kernel.lnx.1.0.r3-rel/kgsl_reclaim.c#L289 [4] https://android.googlesource.com/kernel/common/+/refs/heads/android12-5.10/mm/shmem.c#4310 Signed-off-by: Charan Teja Kalla --- mm/shmem.c | 116 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) diff --git a/mm/shmem.c b/mm/shmem.c index 448f393..1af8525 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -40,6 +40,9 @@ #include #include #include +#include +#include +#include #include "swap.h" static struct vfsmount *shm_mnt; @@ -2344,6 +2347,118 @@ static void shmem_set_inode_flags(struct inode *inode, unsigned int fsflags) #define shmem_initxattrs NULL #endif +static void shmem_isolate_pages_range(struct address_space *mapping, loff_t start, + loff_t end, struct list_head *list) +{ + XA_STATE(xas, &mapping->i_pages, start); + struct folio *folio; + + rcu_read_lock(); + xas_for_each(&xas, folio, end) { + if (xas_retry(&xas, folio)) + continue; + if (xa_is_value(folio)) + continue; + + if (!folio_try_get(folio)) + continue; + if (folio_test_unevictable(folio) || folio_mapped(folio) || + folio_isolate_lru(folio)) { + folio_put(folio); + continue; + } + folio_put(folio); + + /* + * Prepare the folios to be passed to reclaim_pages(). + * VM can't reclaim a folio unless young bit is + * cleared in its flags. + */ + folio_clear_referenced(folio); + folio_test_clear_young(folio); + list_add(&folio->lru, list); + if (need_resched()) { + xas_pause(&xas); + cond_resched_rcu(); + } + } + rcu_read_unlock(); +} + +static int shmem_fadvise_dontneed(struct address_space *mapping, loff_t start, + loff_t end) +{ + LIST_HEAD(folio_list); + + if (!total_swap_pages || mapping_unevictable(mapping)) + return 0; + + lru_add_drain(); + shmem_isolate_pages_range(mapping, start, end, &folio_list); + reclaim_pages(&folio_list); + + return 0; +} + +static int shmem_fadvise_willneed(struct address_space *mapping, + pgoff_t start, pgoff_t long end) +{ + struct folio *folio; + pgoff_t index; + + xa_for_each_range(&mapping->i_pages, index, folio, start, end) { + if (!xa_is_value(folio)) + continue; + folio = shmem_read_folio(mapping, index); + if (!IS_ERR(folio)) + folio_put(folio); + } + + return 0; +} + +static int shmem_fadvise(struct file *file, loff_t offset, loff_t len, int advice) +{ + loff_t endbyte; + pgoff_t start_index; + pgoff_t end_index; + struct address_space *mapping; + struct inode *inode = file_inode(file); + int ret = 0; + + if (S_ISFIFO(inode->i_mode)) + return -ESPIPE; + + mapping = file->f_mapping; + if (!mapping || len < 0 || !shmem_mapping(mapping)) + return -EINVAL; + + endbyte = fadvise_calc_endbyte(offset, len); + + start_index = offset >> PAGE_SHIFT; + end_index = endbyte >> PAGE_SHIFT; + switch (advice) { + case POSIX_FADV_DONTNEED: + ret = shmem_fadvise_dontneed(mapping, start_index, end_index); + break; + case POSIX_FADV_WILLNEED: + ret = shmem_fadvise_willneed(mapping, start_index, end_index); + break; + case POSIX_FADV_NORMAL: + case POSIX_FADV_RANDOM: + case POSIX_FADV_SEQUENTIAL: + case POSIX_FADV_NOREUSE: + /* + * No bad return value, but ignore advice. + */ + break; + default: + return -EINVAL; + } + + return ret; +} + static struct inode *shmem_get_inode(struct mnt_idmap *idmap, struct super_block *sb, struct inode *dir, umode_t mode, dev_t dev, unsigned long flags) @@ -3942,6 +4057,7 @@ static const struct file_operations shmem_file_operations = { .splice_write = iter_file_splice_write, .fallocate = shmem_fallocate, #endif + .fadvise = shmem_fadvise, }; static const struct inode_operations shmem_inode_operations = {